A tactical group wraps up their search after police responded to reports of a man with a gun inside a Seton Medical center building near the hospital, in Daly City, Calif., which turned out to be unfounded on Wednesday April 23, 2014.

A tactical group wraps up their search after police responded to reports of a man with a gun inside a Seton Medical center building near the hospital, in Daly City, Calif., which turned out to be unfounded on Wednesday April 23, 2014.

Officer R. Mussman, right, listens to Andrew Lai as Lai, the owner of the pharmacy inside the evacuated building, expresses concern about it being left unlocked as Jona Gomez, left, waits to get her car out of the restricted area at the scene of what was thought to be a shooting April 23, 2014 in a medical facility in Daly City, Calif.

People with their hands on their heads are cleared from the building as police respond to reports of a gunshot fired inside a Seton Medical center building near the hospital, in Daly City, Calif., on Wednesday April 23, 2014.

All people are cleared out with their hands on their heads the as police respond to reports of a gunshot fired inside a Seton Medical center building near the hospital, in Daly City, Calif., on Wednesday April 23, 2014.

(04-24) 11:06 PDT DALY CITY -- An 84-year-old man was arrested Wednesday night in connection with a gunshot fired earlier in the day inside a medical building in Daly City, police said.

Raymond Iwase was taken into custody at 10 p.m. at his home on Plymouth Circle in Daly City, about 2 1/2 miles from the building that houses about 40 medical practitioners, said police Lt. David Mackriss.

The arrest capped a day in which police initially concluded, after sealing off the neighborhood and searching the building, that no shooting had happened.

Investigators found a gun and ammunition at Iwase's home, police said, though it was not immediately clear whether it was the same firearm allegedly used at the medical building.

Police did not say what the motive might have been for the shooting, in which no one was injured. Iwase was booked at San Mateo County Jail on suspicion of attempted murder. He has declined to speak to reporters.

The incident began about 1:30 p.m., when police responded to the second floor of the medical building at 1500 Southgate Ave. to investigate a doctor's report that there was a man with a gun.

The doctor told police he heard one gunshot and fled, Mackriss said.

Patients and staffers were evacuated, some with their hands over their heads. After a room-by-room search, investigators declared the building clear about 5 p.m., and Mackriss said there were "no suspects and no evidence of any shots fired."

However, police later said they had found bullet fragments near a doorway where the doctor reported seeing the gunman.